Many different kinds of composite structures are currently used in a wide range of applications where it is desirable to provide protection against explosions and projectiles, including, for example, armor systems for personnel, vehicles, and aircraft. Early protective structures tended to rely on a single layer of a hard material, such as metallic or ceramic plates, to provide protection. Ceramic plates provide a weight reduction compared to steel plates, which can increase the mobility of armored vehicles or reduce support requirements in buildings. However, the high rigidity and hardness of ceramic plates makes them vulnerable to brittle fracture from mechanical impacts reducing their effectiveness to multiple strikes. Therefore, such structures could be improved considerably if the ceramic materials were affixed to energy absorbing backing material. Typically, metal or ceramic plates are adhesively secured to a ballistic resistant substrate, such as Kevlar™ or Dyneema™ materials. Continued development in protective systems considers the optimization of protection, weight, maintainability, and cost.
Armoring of vehicles must satisfy seemingly incompatible goals: uncomplicated maneuverable vehicles that can sustain the rigors of combat and the weight of armoring, while maintaining full functionality to perform required missions and maximizing ease of repair to minimize service time. Military and support vehicles in recent combat zones now require protection from increasingly lethal threats. These include ballistic projectiles and explosions that propagate a blast wave and fragments. Studies have shown that a structure exposed to a combination of the blast wave and fragments will collapse more readily than on exposure to the blast wave or fragments alone. Further, distance from the explosion affects the results because fragments arrive before the blast wave at distances beyond three meters from the source. Weight reduction is critical to maintaining maneuverability and flexibility of vehicles to perform their required missions. Further, manufacturability of original articles, availability of material, and reparability in the field is of the utmost importance to maximize mission availability and minimize cost of production and maintenance.